Braking system architectures are known, in particular from document U.S. Pat. No. 6,296,325, that include a plurality of brake controllers (known as electromechanical actuator controllers or EMACs) that are arranged in pairs to provide calibrated power signals to the electromechanical braking actuators of two wheels. One of the EMACs supplies calibrated power signals to one group of actuators of one wheel and also to one group of actuators of an adjacent wheel, the other EMAC providing calibrated power signals to the remaining actuators for both wheels, both EMACs being connected to distinct power supplies so that the loss of one of the EMACs or of one of the power supplies causes only some of the actuators on each wheel to be lost, the remaining actuators continuing to be controlled by the other EMAC.
In that document, the EMACs are said to be “redundant” even though the actuators are each connected to a single EMAC, such that an EMAC failure necessarily condemns the actuators connected to the failed EMAC. No other EMAC takes over control of those actuators in the event of the corresponding EMAC failing. Properly speaking, the EMACs are therefore not redundant. Nevertheless, each of them is arranged to increase the force exerted by the actuators connected to the working EMAC in the event of the associated EMAC failing, thereby at least partially compensating for the loss of the failed EMAC and the associated actuators.
Nevertheless, with such an architecture, the loss of any one EMAC is critical and prevents the aircraft departing since the loss of that EMAC leads to the loss of the associated actuators carried by one of the undercarriages, and the subsequent failure of the EMAC paired therewith and powering the other actuators carried by the same undercarriage would lead to a total loss of braking on all of the actuators of that undercarriage, which is not acceptable.
FIG. 10 of document U.S. Pat. No. 6,402,259 proposes an architecture with EMACs that are genuinely redundant, that are associated in pairs so that both of them control the actuators of an undercarriage, such that even if one EMAC fails, the associated EMAC can control all of the actuators controlled by the failed EMAC.
However, once more, the loss of one EMAC is critical and prevents departure of the aircraft, since any subsequent failure of the EMAC paired therewith would lead to a total loss of braking on all of the actuators carried by one of the undercarriages, which is likewise not acceptable.